Energy performance of buildings Calculation of energy use for space heating and cooling

Transcription

1 ISO TC 163/SC 2 / N02 Date: ISO/FDIS 13790:2006(E) Draft for comments by CEN and ISO WG CEN TC89/WG4/N284 ISO TC 163/SC 2/WG 10 Secretariat: SN Energy performance of buildings Calculation of energy use for space heating and cooling Performance énergétique des bâtiments Calcul des besoins d'énergie pour le chauffage et le refroidissement des locaux Document type: International Standard Document subtype: Document stage: (50) Approval Document language: E C:\DOCUME~1\Jaap\LOCALS~1\Temp\Tijdelijke map 2 voor N284TC89WG4_ISO13790_ zip\N284TC89WG4_ISO13790_ doc STD Version 2.1c

2 Copyright notice This ISO document is a Draft International Standard and is copyright-protected by ISO. Except as permitted under the applicable laws of the user's country, neither this ISO draft nor any extract from it may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, photocopying, recording or otherwise, without prior written permission being secured. Requests for permission to reproduce should be addressed to either ISO at the address below or ISO's member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel Fax copyright@iso.org Web Reproduction may be subject to royalty payments or a licensing agreement. Violators may be prosecuted. ii ISO 2006 All rights reserved

3 Contents Page 1 Scope Normative references Terms and definitions Symbols and abbreviations Outline of the calculation procedures Energy balance of building and systems Main structure of calculation procedure Energy balance at the building level Different types of calculation methods Main characteristics of the different methods Energy balance at the level of the system services Overall energy balances for building and systems Definition of boundaries and zones General Boundary of the building for the calculation Thermal zones Determination of useful floor area, A fl Building energy need for space heating and cooling Calculation procedure Energy need for heating and cooling Length of heating and cooling seasons for operation of season-dependent provisions Heat transfer by transmission Calculation procedure Total heat transfer by transmission per building or building zone Transmission heat transfer coefficients Input data and boundary conditions Heat transfer by ventilation Calculation procedure Total heat transfer by ventilation Ventilation heat transfer coefficients Input data and boundary conditions Internal heat gains Calculation procedure Overall internal heat gains Internal heat gain elements Input data and boundary conditions Solar heat gains Calculation procedure Overall solar heat gains Solar heat gain elements Input data and boundary conditions Dynamic parameters Calculation procedure Dynamic parameters Boundary conditions and input data Indoor conditions...62 ISO 2006 All rights reserved iii

4 13.1 Calculation procedures Boundary conditions and input data Energy use for space heating and cooling Annual energy need for heating and cooling, per building zone Annual energy need for heating and cooling, per combination of systems Total system energy use for space heating and cooling and ventilation systems Report General Input data Results Annex A (normative) Parallel routes in normative references Annex B (normative) Multi-zone calculation with thermal coupling between zones B.1 General B.2 Simple hourly method B.3 Monthly method B.4 All methods: input data Annex C (normative) Full set of equations for simple hourly method C.1 Introduction C.2 Calculation of heat flows from internal and solar heat sources C.3 Determination of the air and operative temperatures for a given value of Φ HC,n C.4 Calculation of air temperature and required heating or cooling power Annex D (normative) Alternative formulation for monthly cooling method D.1 Introduction D.2 Alternative formulation for energy need for cooling D.3 Length of cooling season D.4 Gain utilisation factor for cooling Annex E (normative) Heat loss of special envelope elements E.1 Ventilated solar walls (Trombe walls) E.2 Ventilated envelope elements Annex F (normative) Solar heat gains of special elements F.1 Introduction F.2 Unconditioned sunspaces F.3 Opaque elements with transparent insulation F.4 Ventilated solar walls (Trombe walls) F.5 Ventilated envelope elements Annex G (normative) Climate related data G.1 Common data G.2 Climate data Annex H (informative) Void H.1 xxx Annex I (informative) Simplified methods and standard input data I.1 Introduction I.2 Simplified methods and data related to heat transfer by thermal transmission I.3 Simplified methods and data related to heat transfer by ventilation I.4 Simplified methods and data related to internal heat gains I.5 Simplified methods and data related to solar heat gain I.6 Simplified methods and data related to dynamic parameters I.7 Simplified methods and data related to indoor conditions (internal temperature setpoints) Annex J (informative) Accuracy of the method J.1 Introduction J.2 Propagation of errors J.3 Comparison with actual buildings J.4 Comparison between building designs iv ISO 2006 All rights reserved

5 J.5 Comparison with dynamic numerical models J.6 Comparison between users of the standard J.7 Balanced accuracy J.8 Validation J.9 Validation simple hourly calculation method Annex K (informative) Explanation and derivation of monthly or seasonal utilisation factors K.1 Xxxx K.2 Explanation K.3 Derivation of utilisation factors from dynamic simulations K.4 Relation between overheating and gain utilisation factor Annex L (informative) Worked out example; monthly method L.1 Introduction L.2 Background of example L.3 Example Annex M (informative) Flow charts of the calculation procedures M.1 Introduction M.2 Heating mode, simple situation M.3 Heating mode, detailed situation M.4 Cooling mode, 'medium' case ISO 2006 All rights reserved v

6 Foreword ISO was prepared by Technical Committee CEN/TC 89, Thermal performance of buildings and building components, the secretariat of which is held by SIS, in cooperation with Technical Committee ISO/TC 163, Thermal performance and energy use in the built environment, Subcommittee SC 2, Calculation methods. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association (Mandate M/343), and supports essential requirements of EU Directive 2002/91/EC on the energy performance of buildings (EPBD). ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO was prepared by Technical Committee ISO/TC 163, Thermal performance and energy use in the built environment, Subcommittee SC 2, Calculation methods. This second/third/... edition cancels and replaces the first/second/... edition (ISO 13790:2004), [clause(s) / subclause(s) / table(s) / figure(s) / annex(es)] of which [has / have] been technically revised. vi ISO 2006 All rights reserved

7 Introduction Editorial remarks: Blue highlighted: editorial or technical point of attention, to be solved by the authors Editorial notes: Note that for some part the symbols and subscripts have already been adapted "at the last minute" to the proposed common list of symbols and subscripts for CEN BT WG173 (dd July 8, 2006); but not yet all (in particular not yet in the figures) Note that the numbering of figures, tables and equations has not yet been checked and updated Yellow highlighted: to point the reader to specific changes compared to the ISO/DIS version; the number of changes were too many to mark all changes using the Word revision mode. Consequently, the authors marked only the major changes and if similar changes occur at several locations: only at first location. This standard is one of a series of calculation methods for the design and evaluation of thermal and energy performance of buildings. It presents a coherent set of calculation methods at different levels of detail, for the energy use for the space heating and cooling of a building and the influence of the heating and cooling system losses, heat recovery and the utilisation of renewable energy sources. In combination with other EPBD 1) related standards (see scheme in Figure 1), this standard can be used for the following applications: a) judging compliance with regulations expressed in terms of energy targets (via the design rating, see EN 15203); b) comparing the energy performance of various design alternatives for a planned building; c) displaying a standardised level of energy performance of existing buildings (the calculated rating, see EN 15203); d) assessing the effect of possible energy conservation measures on an existing building, by calculation of the energy use with and without the energy conservation measure (see also EN 15203); e) predicting future energy resource needs on a regional, national or international scale, by calculating the energy use of typical buildings representative of the building stock. References are made to other international standards or to national documents for input data and detailed calculation procedures not provided by this standard. Main changes compared to ISO 13790:2004: Unlike ISO 13790:2004, Thermal performance of buildings Calculation of energy use for space heating whose scope was restricted to simplified methods for space heating, this standard integrates both space 1) DIRECTIVE 2002/91/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 16 December 2002 on the energy performance of buildings ISO 2006 All rights reserved vii

8 heating and cooling and methods with different levels of detail. The most important changes in this standard compared to ISO 13790:2004 are: throughout the whole document statements and equations that were only true for the heating mode have been changed to accommodate both heating and cooling modes; throughout the whole document all texts that were only true for monthly or seasonal calculations have been changed to accommodate monthly, seasonal, as well as hourly calculation methods; the structure of the document has been adapted to maximize the common use of procedures, conditions and input data, irrespective of the calculation method; a monthly (and seasonal) method for cooling, similar to the method in ISO 13790:2004 for heating, has been provided; a simple hourly method for heating and cooling, to facilitate direct introduction of hourly, daily or weekly patterns (e.g. controls, user behaviour), has been included; for dynamic simulation methods, procedures concerning boundary conditions and input data have been included, that are consistent with the boundary conditions and input data for the seasonal, monthly and simple hourly methods; the whole document has been scrutinised to check its applicability within the context of building regulations, which require a minimum of ambiguities and subjective choices; where needed, possibilities are offered for national choices, depending on the purpose/application of the calculations (see list above) and on type or complexity of the building. The flowchart in Figure 1 gives an outline of the calculation procedure and its links with other EPBD related standards. WI 4, etc. refers to the work items covered by Mandate M/343. For titles of these work items see Clause 2. The main inputs needed for this standard are: Transmission and ventilation properties; Heat gains from internal heat sources, solar properties; Climate data; Description of building and building components, systems and use; Comfort requirements (set-point temperatures and ventilation rates); Data related to the heating, cooling, hot water, ventilation and lighting systems: Partition of building into different zones for the calculation (different systems may require different zones); Energy losses dissipated or recovered in the building (internal heat gains, recovery of ventilation heat loss); Air flow rate and temperature of ventilation supply air (if centrally pre-heated or pre-cooled) and associated energy use for air circulation and pre-heating or pre-cooling; Controls. viii ISO 2006 All rights reserved

9 The main outputs of this standard are: Annual energy needs for space heating and cooling; Annual energy use for space heating and cooling; Length of heating and cooling season (for system running hours); Auxiliary energy use for heating, cooling and ventilation systems. Additional outputs are: (Informative) monthly values of energy needs and energy use; (Informative) monthly values of main elements in the energy balance (transmission, ventilation, internal heat gains, solar heat); Contribution of renewable energy sources; System losses (from heating, cooling, hot water, ventilation and lighting systems), recovered in the building. Fout! Objecten kunnen niet worden gemaakt door veldcodes te bewerken. Figure 1 Flow chart of calculation procedure and links with other standards ISO 2006 All rights reserved ix

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11 FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 13790:2006(E) Energy performance of buildings Calculation of energy use for space heating and cooling 1 Scope <check: Not only in Intro (=informative), also in Scope: primarily for EPBD-type of calculations extra attention for reproducibility etc.>this standard gives calculation methods for assessment of the annual energy use for space heating and cooling of a residential or a non-residential building, or a part of it, which will be referred to as "the building". This method includes the calculation of: 1) the heat transfer by transmission and ventilation of the building or building zone when heated or cooled to constant internal temperature; 2) the contribution of internal and solar heat gains to the building heat balance; 3) the annual energy needs for heating and cooling, to maintain the specified set-point temperatures in the building; 4) the annual energy use for heating and cooling of the building, including auxiliary energy for heating, cooling and ventilation, based on input from the relevant system standards referred to in this standard and specified in annex A. The building can have several zones with different set-point temperatures, and can have intermittent heating and cooling. The calculation interval is either one month or one hour. For residential buildings the calculation can also be performed on the basis of the heating and/or cooling season. Monthly calculation gives sufficiently correct results on an annual basis, but the results for individual months close to the beginning and the end of the heating and cooling season can have large relative errors. The standard also gives an alternative simple hourly method, using hourly user schedules (such as temperature set-points, ventilation modes, or operation schedule of movable solar shading). This method produces hourly results, but the results for individual hours or individual months are not validated; the results for individual hours can have large relative errors and for monthly results the same applies as for the monthly method. Also procedures are given for the use of more detailed simulation methods to ensure compatibility and consistency between the application and results of the different types of methods. The standard provides, for instance, common rules for the boundary conditions and physical input data irrespective of the chosen calculation approach. The standard has been developed for buildings that are (assumed to be) heated and/or cooled for the thermal comfort of people, but can be used for other types of buildings or types of use (e.g. industrial, agricultural, swimming pool), as long as appropriate input data are chosen and the impact of special physical conditions on the accuracy is taken into consideration. NOTE 1 For instance because a special model is needed but missing. ISO 2006 All rights reserved 1

12 This also accounts for a section in a building that is dominated by process heat (e.g. indoor swimming pool, computer/servers room, kitchen in restaurant,..). Depending on the purpose of the calculation, it may be nationally decided to provide specific calculation rules for spaces that are dominated by process heat (e.g. indoor swimming pool, computer/servers room or kitchen in restaurant). NOTE 2 For instance in case of building energy certificate and/or building permit; e.g. by ignoring the process heat or use default process heat for certain processes (e.g. shops: freezers, lighting in shop-window). The calculation procedures in this standard are restricted to sensible heating and cooling. The energy use due to humidification shall be calculated in the relevant standard on the energy performance of ventilation systems as specified in annex A; similarly, the energy use due to dehumidification shall be calculated in the relevant standard on the energy performance of space cooling systems as specified in annex A. The calculation shall not be used to decide whether mechanical cooling is needed or not. The main focus of the standard is on the use within the context of building regulations. Consequently, this standard aims to provide the right balance between accuracy, transparency, robustness and reproducibility. To accommodate the application for different situations, this standard offers different choices. For the choices given in this standard where it is explicitly stated that decisions may be made at national level, it is up to national bodies to exclusively choose (assign) a specific option, depending on the region in the country, the type of building and its use, and on the purpose of the assessment. NOTE 3 For instance the choice for a specific option when checking compliance with minimum energy performance requirements and for energy performance certification. Annex J provides some information on the accuracy of the method. This standard is applicable to buildings at design stage and to existing buildings. The input data directly or indirectly called for by this standard should be available from the building files or the building itself. If it is not the case, it is explicitly stated at relevant places in this standard that it may be decided at national level to allow for other sources of information. In this case the user shall report which input data has been used and from which source. NOTE 4 For instance for the purpose of calculating the energy performance rating for a building energy performance certificate. The formulation aims to exclude the misuse of this escape route for those cases (e.g. very recently built buildings or buildings with a "dossier-as-built") where the full input data should be available. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 7345:19xx, Thermal insulation Physical quantities and definitions ISO 6946:2006 2), Building components and building elements Thermal resistance and thermal transmittance Calculation method ISO :2006 2), Thermal performance of windows, doors and shutters Calculation of thermal transmittance Part 1: General ISO 13370:2006 2), Thermal performance of buildings Heat transfer via the ground Calculation methods 2) Revised version to be submitted for final vote in ISO 2006 All rights reserved

13 ISO 13786:2006 2), Thermal performance of buildings Dynamic thermal characteristics Calculation method ISO 13789:2006 2), Thermal performance of buildings Transmission and ventilation heat transfer coefficients Calculation method ISO :2006, Hygrothermal performance of buildings Calculation and presentation of climatic data Part 4: Hourly data for assessing the annual energy use for heating and cooling ISO 9050:19xx, Glass in building Determination of light transmittance, solar direct transmittance, total solar energy transmittance, ultraviolet transmittance and related glazing factors ISO 15099:2003, Thermal performance of windows, doors and shading devices Detailed calculations EN 410, Glass in buildings Determination of luminous and solar characteristics of glazing EN , Solar protection devices combined with glazing Calculation of solar and light transmittance Part 2: Detailed calculation method pren 13947, Thermal performance of curtain walling Calculation of thermal transmittance wi 4draft EN ), Energy performance of buildings Assessment of energy use and definition of ratings wi 7draft EN ), Heating systems in buildings - Method for calculation of system energy requirements and system efficiencies Part 1: General wi 8draft EN ), Heating systems in buildings - Method for calculation of system energy requirements and system efficiencies Part 2.1: Space heating emission systems wi 9draft EN ), Heating systems in buildings - Method for calculation of system energy requirements and system efficiencies Part 2.2.1: Boilers Part 2.2.2: Heat pumps Part 2.2.3: Heating generation Thermal solar systems Part 2.2.4: Performance and quality of CHP Part 2.2.5: Performance and quality of district heating and large volume systems Part 2.2.6: Performance of other renewables (heat and electricity) Part 2.2.7: Space heating generation Biomass combustion systems wi 10draft EN ), Heating systems in buildings - Method for calculation of system energy requirements and system efficiencies Part 2.3: Space heating distribution systems wi 11draft EN ), Heating systems in buildings - Method for calculation of system energy requirements and system efficiencies Part 3.1: Domestic hot water systems, including generation efficiency and the tap water requirements wi 13draft EN ), Energy performance of buildings Energy requirements for lighting Part 1: Lighting energy estimation wi 17draft EN ), Thermal performance of buildings Calculation of energy use for space heating and cooling General criteria and validation procedures for detailed calculations wi 20/21draft EN ), Ventilation for buildings Calculation methods for energy requirements due to ventilation systems in buildings wi 18/19draft EN ), Ventilation for buildings Calculation methods for the determination of air flow rates in buildings including infiltration 3) To be submitted for final vote in 2006 ISO 2006 All rights reserved 3

14 EN 13465, Ventilation for buildings Calculation methods for the determination of air flow rates in dwellings<replaced by EN 15242> wi 12draft EN ),, Ventilation for buildings Calculation of room temperatures and of load and energy for buildings with room conditioning systems System energy calculation 3 Terms and definitions For the purposes of this standard, the terms and definitions in ISO 7345 and the following apply. 3.1 calculation period discrete time interval for the calculation of the energy need for heating or cooling NOTE The discrete time interval for the calculation is one hour or one month. For residential buildings the calculation may also be performed for the heating and/or cooling season. 3.2 heating and cooling season period of the year during which a significant amount of energy for heating or cooling is needed NOTE The lengths of the heating and cooling seasons are determined in different ways, depending on the calculation method. The season lengths are used to determine the operation period for e.g. auxiliary energy and special ventilation (e.g. free or night time cooling) provisions. 3.3 temperature external temperature temperature of external air NOTE For transmission heat transfer calculations, the radiant temperature of the external environment is supposed equal to the external air temperature; long-wave radiation to the sky, from building elements facing the sky, is calculated separately, see and/or internal temperature arithmetic average of the air temperature and the mean radiant temperature at the centre of the considered zone NOTE This is the approximate operative temperature according to ISO 7726, Ergonomics of the thermal environment Instruments for measuring physical quantities. This value is close to the dry resultant temperature in EN ISO set-point (of the internal) temperature minimum intended internal temperature, assumed for the calculation of the energy need for heating, or maximum intended internal temperature, assumed for the calculation of the energy need for cooling. NOTE The values are specified at national level, depending on the type of space and purpose of the calculation. See also definition of conditioned space. For monthly and seasonal methods: the value of the set-point can include adjustment for intermittency, as specified in set-back temperature set-point temperature to be maintained during reduced heating and/or cooling periods 3.4 conditioned space room or enclosure that for the purpose of the calculation is assumed to be heated and/or cooled to given setpoint temperature or set-point temperatures. 4 ISO 2006 All rights reserved

15 NOTE The conditions are specified nationally, depending on the type of space and purpose of the calculation. 3.5 unconditioned space room or enclosure which is not part of the conditioned space 3.6 (building) energy need for heating or cooling heat to be delivered to, or to be extracted from, the conditioned space by a heating or cooling system to maintain the set-point temperature during a given period of time NOTE The energy need may include additional heat transfer resulting from non-uniform temperature distribution and non-ideal temperature control, if they are taken into account by increasing (decreasing) the set-point temperature for heating (cooling) and not included in the heat transfer due to the heating (cooling) system. 3.7 energy auxiliary energy electric energy used by heating, cooling and/or domestic water systems to transform and transport the delivered energy into the useful energy NOTE This includes energy for fans, pumps, electronics, etc., but not the energy that is transformed. Pilot flames are considered as part of the energy use by the system energy use for space heating or cooling <1) check new common definitions (in U.D. expected July 2006) 2) check if output uses correct terms> energy input to the heating or cooling system, including auxiliary energy and thermal system losses, to satisfy the energy need for heating or cooling respectively NOTE In contrast with delivered energy, energy use covers non-renewable and renewable energy sources delivered energy for space heating or cooling <check new common definitions (in U.D. expected July 2006)> energy supplied to the building through the building boundary from the last market agent NOTE See EN 15203/15315 for more explanation. 3.8 intermittent heating or cooling heating or cooling pattern where normal heating or cooling periods alternate with periods of reduced or no heating or cooling 3.9 Unoccupied period Period of several days or weeks without heating or cooling, e.g. due to holidays conditioned zone part of the conditioned space with a given set-point temperature or set-point temperatures, throughout which the internal temperature is assumed to have negligible spatial variations and which is controlled by the same systems for heating, cooling and ventilation 3.11 (calculation) zone part of the conditioned space that for the purpose of the calculation is assumed to form a conditioned zone ISO 2006 All rights reserved 5

16 3.12 (building) heat transfer coefficient NOTE 1 Definitions from ISO (building) heat transfer coefficient (general) factor of proportionality of heat flow governed by a temperature difference between two environments; specifically used for heat transfer coefficient by transmission or ventilation NOTE In contrast with a heat gain, the driving force for heat transfer is the difference between the temperature in the considered space and the temperature of the environment at the other side (in case of transmission) or the supply air temperature (in case of ventilation) transmission heat transfer coefficient heat flow rate due to thermal transmission through a building elementconstruction, divided by the temperature difference between the environment temperatures on either side of the elementconstruction NOTE By convention, the sign of the heat flow is positive if the heat flow direction is outgoing from the considered space (heat loss) ventilation heat transfer coefficient heat flow rate due to air entering the space either by infiltration or ventilation, at (supply) temperature different from the air temperature in the space, divided by the temperature difference between the internal air and the supply air temperature NOTE The sign of the coefficient is always positive. By convention, the sign of the heat flow is positive if the supply air temperature is lower than the internal air temperature (heat loss) heat gains heat gains (general) heat generated within or entering into the conditioned space from sources other than energy intentionally utilised for heating, cooling or hot water preparation NOTE 1 The sources include internal heat sources and solar heat sources. The heat extracted from the building, from negative sources (sinks), is included as gain with a negative sign. In case of heat gains, the difference between the temperature of the considered space and the temperature of the source is not the (prime) driving force for the heat flow. This is the basic difference with heat flows due to transmission or ventilation heat transfer;.see also annex K and [2]. NOTE 2 For summer conditions heat gains with a positive sign constitute extra heat load to the space (and vice versa) internal heat gains heat provided within the building by occupants (sensible metabolic heat) and by appliances such as lighting, domestic appliances, office equipment, etc., other than energy intentionally utilised for heating, cooling or hot water preparation NOTE Including energy dissipated by space heating and cooling systems and hot water system that is not considered as utilised for heating, cooling or hot water preparation. Including heat from (warm) or to (cold) process sources that are not controlled for the purpose of heating or cooling or domestic hot water preparation. The heat extracted from the building, from the indoor environment to cold sources (sinks), is included as gain with a negative sign solar heat gains heat provided by solar radiation entering, directly or indirectly (after absorption in building elements), into the building through windows, opaque walls and roofs, or passive solar devices such as sunspaces, transparent insulation and solar walls NOTE Active solar devices such as solar collectors are considered as part of the heating system. 6 ISO 2006 All rights reserved

17 3.14 solar irradiation incident solar heat per area over a given period 3.15 gain utilisation factor reduction factor on the total monthly or seasonal heat gains into the building or building zone applied in the monthly or seasonal calculation to obtain the resulting reduction of the building energy need for heating NOTE Or applied in the monthly or seasonal heat balance applied in the monthly or seasonal calculation of the building energy need for cooling if the alternative method described in annex D is used 3.16 loss utilisation factor reduction factor on the total monthly or seasonal heat transfer from the building or building zone applied in the monthly or seasonal monthly or seasonal calculation to obtain the resulting reduction of the building energy need for cooling NOTE The traditional term "loss", which originally refers to the heating mode only, is retained for the utilisation factor for losses; if the losses are "negative", there is no utilisation calculation with coupled zones multi-zone calculation with thermal coupling between zones: any heat transfer by thermal transmission and/or by ventilation and/or by air infiltration between zones is taken into account 3.18 calculation with uncoupled zones multi-zone calculation without thermal coupling between zones: any heat transfer by thermal transmission or by ventilation or by air infiltration between zones is not taken into account 3.19 projected area of solar collecting elements (e.g. windows) area of the projection of the surface of the element on a plane parallel to the transparent or translucent part of the element NOTE In case of non-flat elements: the area of the imaginary smallest plane connecting the perimeter of the element 3.20 projected area of frame elements (e.g. window frames) area of the projection of the frame element on a plane parallel to the glazing or panel that is held by the frame 3.21 thermal technical system losses Thermal system losses from the technical equipment for heating, cooling and domestic hot water (not including lighting and ventilation) to its surroundings and which is not directly taken into account within the (sub-)system NOTE The system losses can become an internal heat source or sink in the building in which case (part of) the system loss may be recovered 3.22 recoverable system losses part of the system losses which may be recovered to lower the energy use for heating or the energy use for cooling respectively ventilation heat recovery heat recovered from the exhaust air ISO 2006 All rights reserved 7

18 3.24 heat balance ratio Monthly or seasonal heat gains divided by the monthly or seasonal heat transfer 4 Symbols and abbreviations <Updated to the common list of symbols and subscripts for CEN BT WG173, version July 8, 2006, but to be checked and cleaned> Table 1 Symbols and units Symbol Quantity Unit A area m² a numerical parameter in utilisation factor - B correction factor for an unconditioned adjacent space - C effective heat capacity of a conditioned space J/K c specific heat capacity J/(kg K) d layer thickness m F factor - g total solar energy transmittance of a building element - E sol Solar irradiance W/m 2 E Energy MJ H heat transfer coefficient W/K h surface coefficient of heat transfer W/(m² K) L length m N number Q quantity of heat MJ R thermal resistance m² K/W T thermodynamic temperature K t time, period of time Ms U thermal transmittance W/(m² K) V volume of air in a conditioned zone m³ q airflow rate m³/s Φ heat flow rate, thermal power W Ζ heat transfer parameter for solar walls W/(m² K) α absorption coefficient of a surface for solar radiation - γ Heat balance ratio - ε emissivity of a surface for long-wave thermal radiation - η efficiency, utilisation factor - κ factor related to heat losses of ventilated solar walls - θ Celsius temperature C ρ density kg/m³ σ Stefan-Boltzmann constant (σ = 5, ) W/(m² K 4 ) τ time constant h χ heat capacity per area J/(m² K) NOTE Hours can be used as the unit of time instead of seconds for all quantities involving time (i.e. for time periods as well as for air change rates), but in that case the unit of energy is Watt-hours [Wh] instead of Joules. In most equations MJ are used instead of J for quantities of heat or energy and Ms instead of seconds for time. 8 ISO 2006 All rights reserved

19 Table 2 Subscripts <Updated to the common list of symbols and subscripts, version July 8, 2006, but to be checked and cleaned> C cooling, capacity, e exterior, envelope r radiative; recovered calculation, convective C,n cooling need, or building i Internal (temperature) red reduced need for cooling f frame gr ground H heating s supply (of air) H,n heating need, or building sh shading need for heating HC,n Heating and/or cooling need; hol Holidays, long unoccupied se surface external building need for heating and/or cooling period L Lighting (system) V Ventilation (system) si surface internal W hot water (system or need) Tot Total ss surface-sky average Th Thermal f form, final gn gains ls loss h hemispherical sys system tr Transmission (heat transfer) i,j,k,m,n dummy integers ve Ventilation (heat transfer) l layer int Internal (heat gains) ut utilised sol Solar (heat gains) O outdoor obstacles P related to power m metabolic, month, mass nut Non-utilised mn mean u unconditioned a air an annual A appliances o overall w window aux auxiliary p partition wall y, z zone number bh boost heating pp peak power perpendicular c structure ps permanent shading 0 base; reference d design; daily, direct 5 Outline of the calculation procedures 5.1 Energy balance of building and systems The building energy needs for heating and cooling of the building are calculated on the basis of the heat balance of the building or building zones. This energy need for heating and cooling is the input for the energy balance of the heating and cooling system. The energy balance is split into the energy or heat balance at the building level and the energy balance at the system level. A multi-step calculation may be required, to be defined at national level, for instance to account for interactions between different zones (e.g. sharing the same system(s) and/or dissipation from the same ISO 2006 All rights reserved 9

20 system) or between the systems and the building energy balance (e.g. dissipated heat from systems affecting the heat balance of the building), see Main structure of calculation procedure The main structure of the calculation procedure is summarised below. More details on the calculation procedures are presented in the relevant individual clauses. 1) Choose the type of calculation method, according to ) Define the boundaries of the total of conditioned spaces and the unconditioned spaces, according to ) If required, define the boundaries of the different calculation zones, according to ) Define the indoor conditions for the calculations (clause 13) and the external climatic (annex G) and other environmental data inputs. 5) Calculate, per period and building zone, the energy need for heating, Q H,n, and the energy need for cooling, Q C,n. 6) Combine the results for different periods and different zones serviced by the same systems and calculate the energy use for heating and for cooling taking into account the dissipated heat of the heating and cooling systems, according to Clause 14. Combine the results for different building zones with different systems. 7) Calculate the operational length of the heating and cooling season, according to ) Depending on the application and type of building (to be decided nationally), it may be required to perform the calculation of the energy need for heating and cooling in multiple steps, for instance to account for interactions between the building and the system, or between adjacent zones. The procedures are given in Properties or (conservative) default values can be different for the heating and cooling mode. With the monthly method, heating and cooling in same month can be calculated by calculating 12 months heating mode and 12 months cooling mode. NOTE 1 For the calculation steps, see Figure ISO 2006 All rights reserved

21 EN ISO 13790, Summary Illustrated for three zones, with two sets of (H, C, V) systems servicing different zones version: to EN and EN EN ISO Recombine whole building 7 Energy use of Heating, Cooling and Ventilation Systems (systems 1) 6 idem (systems 2) Recombine zones per system - 5 EN EN EN EN15241 Energy needs for heating and cooling (zone 1) 4 Heat transfer rates and heat/cold sources idem (zone 2) idem (zone 2) idem (zone 3) idem (zone 3) System contribution to internal heat gains Extra free or night ventilation for cooling zone 1 3 zone 2 zone 3 systems 1 systems 2 Partitioning of building into zones for calculation Vent.system heat recovery 2 Dissipated heat from systems Building boundaries 1 Data Data EN 15316, EN 15243, EN , EN 15242, EN15241, EN Heating, hot water, cooling, lighting, ventilation and building automation systems Project data (building, systems, use, surroundings, location) EN 15242, EN ISO 6946 etc.(!), EN 15265, EN 15251, etc. transmission and air flow properties, solar properties, validation, climate, etc. Figure 2 Flow chart of main calculation steps 5.3 Energy balance at the building level The energy (heat) balance at the building or building zone level includes the following terms (only sensible heat is considered): transmission heat transfer between the conditioned space and the external environment, governed by the difference between the set point temperature (temperature of the conditioned space) and the external temperature; transmission and ventilation heat transfer between adjacent zones, governed by the difference between the set point temperature (temperature in the conditioned zone) and the internal temperature in the adjacent space; ISO 2006 All rights reserved 11

22 ventilation heat transfer (by natural ventilation or by a mechanical ventilation system), governed by the difference between the set point temperature (temperature in the conditioned space) and the supply air temperature; internal heat gains (including negative gains: from heat sinks), for instance from persons, appliances, lighting and heat dissipated in or absorbed by heating, cooling, hot water or ventilation systems; solar heat gains (which can be direct, e.g. through windows, or indirect, e.g. via absorption in opaque building elements); storage of heat in, or release of stored heat from, the mass of the building; energy need for heating: if the building or zone is heated, a heating system supplies heat in order to raise the internal temperature to the required minimum level (set-point for heating); energy need for cooling: if the building or zone is cooled, a cooling system extracts heat in order to lower the internal temperature to the required maximum level (set-point for cooling). NOTE The heat transfer to the external environment is negative when the external temperature is higher than the internal temperature. The building energy balance may also include energy recovered in the building from various sources, such as recovered ventilation heat losses. The calculation procedures in this standard are restricted to sensible heating and cooling; see also 5.6. In the heat balance over a longer period (e.g. a month) the accumulation term can be ignored. 5.4 Different types of calculation methods There are two basic types of method: quasi-steady state methods, calculating the heat balance over a sufficiently long enough time to ignore heat stored and released (typically: one month or a whole season), but taking the dynamic effects into account by an empirically determined gain and/or loss utilisation factor; dynamic methods, calculating the heat balance with short periods (typically one hour); taking into account the heat stored in and released from the mass of the building. This standard covers three different types of methods: A fully prescribed monthly quasi-steady state calculation method (plus as a special option: a seasonal method) A fully prescribed simple hourly dynamic calculation method; Calculation procedures for detailed (e.g. hourly) dynamic simulation methods. A maximum consistency in the application (and thus in the results) of these three types of methods is ensured by a maximum of common procedures and descriptions, boundary conditions and input data. The monthly calculation gives correct results on an annual basis, but the results for individual months close to the beginning and the end of the heating and cooling season can have large relative errors. The alternative simple method, for hourly calculations, has been added to facilitate the calculation using hourly user schedules (such as temperature set-points, ventilation modes, operation schedule of movable solar shading and/or hourly control options based on outdoor or indoor climate conditions). This method produces 12 ISO 2006 All rights reserved

23 hourly results, but the results for individual hours are not validated and individual hourly values can have large relative errors. The procedures for the use of more detailed simulation methods ensure compatibility and consistency between the application of different types of methods. The standard provides for instance common rules for the boundary conditions and physical input data irrespective of the chosen calculation approach. At national level it may be decided which of these three types of methods is or are allowed to be used, depending on the application (purpose of the calculation) and building type. NOTE This choice will typically depend on the use of the building (residential, office, etc.), the complexity of the building and/or systems, the application (EP requirement, EP certificate or recommended EP measures, other). See annex J: about the need to maintain a balance between accuracy, transparency, robustness and reproducibility. 5.5 Main characteristics of the different methods Dynamic methods In the dynamic methods an instantaneous surplus of heat during the heating period has the effect that the internal temperature rises above the set-point, thus removing the surplus heat by extra transmission, ventilation and accumulation, if not mechanically cooled. Also, a thermostat setback or switch-off may not directly lead to a drop in the internal temperature, due to the inertia of the building (heat released from the building mass). A similar situation applies to cooling. A dynamic method models the thermal resistances, thermal capacitances and internal and solar heat gains in the building or building zone. There are numerous methods to do so, ranging in complexity from simple to very detailed. There are other standards (e.g. pren wi 17) describing detailed simulation methods or performance criteria for such methods. This standard provides the environment of standardised boundary conditions and standardised input and output data that enables compatibility and consistency between the different methods. In this standard one simple hourly method is fully specified: a three node hourly method Quasi-steady state methods In the quasi-steady state methods, the dynamic effects are taken into account by introducing correlation factors: For heating, a utilisation factor for the internal and solar heat gains takes account for the fact that only part of the internal and solar heat gains is utilised to decrease the energy need for heating, the rest leading to an undesired increase of the internal temperature above the set-point. NOTE 1 See annex K for a more detailed explanation of the concept of the gain utilisation factor for heating. The effect of thermal inertia in case of intermittent heating or switch-off is taken into account separately; see Clause 13. For cooling there are two different ways to represent the same method: a) utilisation factor for losses (mirror image of the approach for heating) A utilisation factor for the transmission and ventilation heat transfer takes account of the fact that only part of the transmission and ventilation heat transfer is utilised to decrease the cooling needs, the non-utilised transmission and ventilation heat transfers occur during periods or intervals (e.g. nights) when they have no effect on the cooling needs occurring during other periods or moments (e.g. days). b) utilisation factor for gains (similar as for heating) A utilisation factor for the internal and solar heat gains takes account for the fact that only part of the internal and solar heat gains is compensated by thermal heat transfer by transmission and ventilation, ISO 2006 All rights reserved 13

24 assuming a certain maximum internal temperature. The other ( non-utilised ) part leads to cooling needs, to avoid an undesired increase of the internal temperature above the set-point. NOTE 1 See annex K for a more detailed explanation of the concept of the gain or loss utilisation factors for cooling. The effect of thermal inertia in case of intermittent cooling or switch-off is taken into account separately; see Clause 13. This standard specifies in the category of quasi-steady state methods a monthly and seasonal method for heating and cooling (presentation type a). The alternative formulation for the monthly cooling method (presentation type b) is presented in Annex D. More details are presented in the next clauses. 5.6 Energy balance at the level of the system services The building energy need for heating and cooling is satisfied by the energy supply from the heating and cooling systems. At the system level the energy balance for heating and cooling, if applicable, includes: energy need for heating and cooling of the building or building zone; energy from renewable energy systems; generation, storage, distribution, emission and control losses of the space heating and cooling systems; energy input to the space heating and cooling systems; special: energy output from the space heating or cooling systems (export; e.g. electricity from a combined heat and power installation). The system energy balance may also include energy recovered in the system from various sources. The system energy use is described in Clause 14. More details on the energy use at system level are provided in the relevant system standards, according to annex A. The calculation procedures in this standard are restricted to sensible heating and cooling. The energy use due to humidification shall be calculated in the relevant standard on the energy performance of ventilation systems as specified in annex A; similarly, the energy use due to dehumidification shall be calculated in the relevant standard on the energy performance of space cooling systems as specified in annex A. 5.7 Overall energy balances for building and systems The main terms of the (time-average) energy balance for heating and cooling are schematically illustrated in a series of diagrams in annex M. 6 Definition of boundaries and zones 6.1 General The procedures in this clause apply to all calculation methods: seasonal, monthly, simple hourly and dynamic simulation methods. 14 ISO 2006 All rights reserved